In most communication systems, an Analog to Digital Converter (ADC) is usually provided in a downlink. The ADC can convert analog signals into digital signals which are suitable for computer processing. Correspondingly, a Digital to Analog Converter (DAC) is provided in an uplink of the communication system. The DAC can in turn convert digital signals into analog signals.
Successive Approximation type Analog to Digital Converter (SAR ADC) is a widely used converter. The SAR ADC includes a DAC and a control circuit, where the DAC built in the SAR ADC can calibrate an output of the SAR ADC under control of the control circuit. Therefore, in an application of the SAR ADC, two DACs are configured in both of the uplink and the downlink of the communication system, which increases chip area of the converting circuit and chip cost.